Thursday, 15 March 2018

Wireless access point bird box

My current nestbox cameras are mostly raspberry pi-based with either a webcam or raspberry pi (RasPi) camera module to record and/or to stream digital video to a web-browser or CCTV software on a separate PC.  Power is via 'Power over ethernet' (PoE) where one ethernet cable provides power and a means to transmit the digital video.  Cable runs are approx 50m and 80m.

Using this setup, I'm limited to one camera per cable run:

Solution: The Wireless Point access bird box or 'WAP-Box'

I've taken an existing raspberry Pi (Raspberry Pi 2, model B)-based bird box, added a wifi dongle and set it up as a wifi access point (as per these instructions).  This is the 'WAP-Box', which helpfully can still be used to run its camera as well as being a wireless access point for other nearby devices.

In this setup, 48v PoE ethernet cable goes to the base of the tree.  At the tree base is a junction box where the cable is split out to ethernet-only and power, dropped to 5v using a TP-Link PoE splitter.  The 5V output is then used to power a  Mini USB hub using a  female USB to female barrel socket adapter, and the barrel connector supplied with the TP-link PoE splitter.  The usb hub can be used to power up to 4 devices. (note that this PoE kit also includes the power injector used in the house).
So, this didn't work well.  I ended up dropping the 48v feed to 12v, an splitting this out to a 'junction box' at the bottom of the tree as I didnt fancy climbing a tree each time I wanted to  connect/disconnect a device....  12v feeds are ...

1) Recombined with ethernet for wired, PoE and sent to the 'WAP-box' which is up a tree.  This a based around a wired ethernet Raspberry pi 2B with wifi dongle.  The 12 v PoE feed powers the Raspberry Pi another TP-link PoE splitter with voltage dropped to 5v   The power cable was hacked from micro USB cable (keep the micro end to be used later) and a DC barrel connector.  I couldnt find a link for the PoE injector I used, but it came with a print server ages ago and had been in the 'may come in useful' drawer.

2) The additional WiFi 'Satellite NestBoxes':
Birch log box small tit box described here
Robin box described here

These take a 5v 12v feed via cables made from a length of black 2-core bell wire and the same microusb and DC barrel connectors linked to above.  The cables power a Raspberry Pi Zero-W + Raspberry Pi v2 IR camera module combo in each box which will have a couple of IR and visible LEDs to for illumination. The satellite boxes are pre-configured to connect to the WAP-box, and thus can save any captured video direct to my home network, so I dont need to worry about the little Raspi ZeroW's running out of space on their SD cards.
This didnt work well due to lag / poor network connection.  In the end I ended up writing video locally to the PiZero's SD cards, and archiving off daily to the local network, which can all be automated.

This all currently works on the bench with 4 concurrently running camera setups using PikrellCam software, and will be going up in the next couple of weeks once their various boxes are completed.  In testing, the Pi Zero-W can 'see' the WAP-box up to about 30m away - my main concern is that if the 12v cable runs are too long the voltage drop may lead to instability of the Pi Zero-W's, so that is likely to limit the cable run distance rather than the strength of the WiFi signal.  I also need to have a think about the current load on the 48v power injector at the house end...

More to follow once some boxes are up...

Of note is that the Raspbery Pi foundation recently released a new version of the highest performing version, called the Model 3B+.  This is interesting this context as it could potentially make a better WAP-box core since it has a faster ethernet connection.  Currently, simultaneously live streaming 4 Raspi-zeros via the existing Pi2 Model B is a bit choppy, which may be due to a bottleneck at the WAP-box's ethernet connection... or this could just be me using this as an excuse to play with one...

Satellite box 1, 'Robin Box' described in this post
Satellite box 2 'Birch log box' described in this post


  1. Absolutely brilliant! And I look forward to seeing lots of video from you this year.

    Re: 5V supply to PiZero's: I would suggest you check the actual voltage at each Pi using a DVM, with 30m cable & using worst case conditions (e.g. lights on, streaming, remote pc displaying stream). Could you run 48V instead of 5V and then drop to 5V? I guess most of the common regulators may not stand a 48V input voltage.

    Re: choppy video: I'd suggest checking the WiFi data rates; from PiZero back to WAP, and from WAP back to house pc. Take a look at my post:

    You may also need to consider the mounting and orientation of boxes and PiZeros within the box (e.g. if a box is on a tree trunk, facing away from the WAP, its signal may be attenuated by the tree trunk).

    Good luck, its an interesting project.

  2. so, after testing a 'satellite' box with 4m speaker cable... it does not work at 5v. Interestingly, there is no measurable voltage drop from 5.14V over that cable, but no joy. I changed it so that it goes as follows: House (50m, 48v) -> junction box (drop to 12v) -> satellite box (4m test, 12v) then drop 12v to 5v using a recom r-78b5.0 1.5 converter. This works, not clear why given that I cant demonstrate a voltage drop when trying 5v over speaker cable. I suspect its my choice of cable, since the WAP box works fine over a couple of meters of ethernet at 5v transmission. A bit of a pain, as it adds a bit more complexity at £10 extra cost per satellite box.

  3. The 5V problem seems odd (did the Pi even boot?) but I think the revised configuration (48V>12V>5V) will prove more satisfactory.

  4. booted, and rebooted and rebooted etc etc